The invention relates to a slide ring seal, including a slide ring and a counter-ring, the slide ring and the counter-ring sealingly contacting each other at sealing surfaces so as to be relatively twistable and acted upon by spring tension under axial prestressing, the slide ring, via a first sealing ring, being sealingly connected in a rotatably fixed manner to a first drive ring and/or the counter-ring, via a second sealing ring, being sealingly connected in a rotatably fixed manner to a second drive ring.
A slide ring seal of this type is known from German Patent 196 37 813 A1. The sealing rings disclosed there each have free surfaces that are impinged upon by the medium to be sealed off.
The invention is directed to the objective of refining a slide ring seal of the type cited above, such that, during normal use of the slide ring seal, a swelling of the sealing rings and a resulting spreading of the free surfaces of the sealing rings is substantially prevented or is reduced to a minimum. Consequently, and generally irrespective of the medium to be sealed off, an invariably rotatably fixed coordination of slide ring and counter-ring with respect to the respective drive ring is assured for a long service life.
To achieve the objective, provision is made that the first and/or the second sealing ring, on the side facing the medium to be sealed off, is essentially completely overlapped by a flange of the respective drive ring. The specific flange preferably contacts the surface of the respective sealing ring, touching it lightly. The coordination of the flange and the surface of the sealing ring, at a very small distance from each other, is also possible. In the configuration according to the invention, it is advantageous that the first and/or second sealing ring have virtually no free surfaces which come in contact with the medium to be sealed off. A swelling of the material of the sealing rings is therefore reduced to a minimum. In any case, as a result of the configuration according to the invention, the following are to be reliably avoided: a reduction in the prestressing of the sealing rings between the slide ring and the first drive ring and/or between the counter-ring and the second drive ring due to a swelling of the respective sealing rings; a spreading of the free surfaces; and the resulting danger that the slide ring and/or the counter-ring will twist with respect to the respective sealing ring. The rotatably fixed coordination of slide ring and/or counter-ring to the respective drive ring is therefore always dependably assured, irrespective of the medium to be sealed off.
The sealing rings are made of an incompressible material. As a result of the fact that the material of the sealing rings cannot spread due to the flange, a slight swelling of the sealing rings causes an intensified elastic prestressing between the slide ring and the first drive ring and/or between the counter-ring and the second drive ring.
The first and/or second sealing ring is preferably made of a polymer material, for example FKM (fluoropolymerizate). The slide ring and/or the counter-ring are usually made of a brittle material such as carbon or silicon carbide, and they are enclosed, at a radial distance, by the corresponding drive rings, which are preferably made of a rust-free metallic material. The respective sealing rings are arranged inside the gap formed by the distance. Undesirably high mechanical stresses, reducing service life, exerted on the slide ring and/or the counter-ring by the corresponding drive rings, are avoided as a result of the sealing rings.
The first sealing ring can be provided with an armoring reinforcement, which is entirely enclosed by polymer material. The armoring is mostly made of steel and is protected by the complete casing, for example from corrosion by the medium to be sealed off. The armoring brings about a greater stiffness of the first sealing ring and, as a result, an improved sealing between the spaces to be sealed off from each other.
The first and/or the second sealing rings have end faces, facing each other, which on the side facing the medium to be sealed off sealingly contact the respective flange of the drive ring, under elastic prestressing. In this context, it is advantageous that a volume increase of the sealing rings, upon impingement by the medium to be sealed off, is prevented. An impingement of the sealing rings by the medium to be sealed off brings about an increasing prestressing on the slide ring and/or the counter-ring, as a result of the sealing rings being clamped in the drive rings.